1. Field of the Invention
The present invention relates to hatch systems for use on tanks, and more particularly, to remotely operated hatch systems for tanks and bulk carriers, such as those carried by trucks and trains.
2. Background Information
Commercial tanks, also commonly known as “tankers” and “bulk carriers”, are widely used for transporting both liquid and dry goods. Tanks are configured with hatches to open and close an opening in the top of the tank, to access to the interior of the tank. Opening or closing the hatch often requires an operator to climb on top of the tank to manually release securing or locking mechanisms that keep the hatch closed. The operator then must lift or otherwise move the hatch cover to open the hatch. This operation can be hazardous to the operator, because a fall from the typical height of the top of the tank may cause injury, and because the contents of many such tanks often include vapors or gases which may be toxic or unpleasant. Inclement weather and moisture or ice on the top of the tank can increase the danger associated with climbing up on the tank and operating the hatch securing mechanism.
Since some types of goods transported by tank are transported under pressure, some tanks have opening closures that must withstand a pressure differential between internal and external pressures. For example, some tanks are used for the storage or transportation of granular or powder form dry bulk goods such as flour, salt, cement, lime, and cereal grains. These dry bulk goods are pneumatically transferred into the tank from a storage facility, via a pneumatic transfer system. Pneumatic transfer systems do not work properly unless the closure on the access port of the tank can maintain a pressure differential between the interior pressure of the tank and exterior pressure on the tank.
Automated hatch opening and closing systems have been devised in the prior art to allow remote operation of a hatch. Some of these systems can be retrofit on existing manually-operated hatches. Many preexisting automated hatch systems suffer from a number of disadvantages. One known disadvantage of these prior art hatch systems is that these systems are prone to leak when pressurized. Another known disadvantage to these systems is that significant modification is required to retrofit the preexisting tanks, which can be costly and time consuming to retrofit. Another known disadvantage of the prior art systems is that they may be complicated to install and somewhat expensive to purchase. A further known disadvantage of the prior art systems is that they may open the hatch vertically, thus potentially obstructing tank-filling equipment.